dactyl (n.)

metrical foot, late 14c., from Latin dactylus, from Greek daktylos, a unit of measure (a finger-breadth), also "a fruit of the date tree, a date," literally "finger" (also "toe"), a word of unknown origin. The metrical use (a long syllable followed by two short ones) is by analogy with the three joints of a finger. In English versification it refers to an accented syllable followed by two unaccented. The "date" sense also sometimes was used in early Modern English.